There’s some acceptance in London that, if the Eurozone is to get itself out of its current hole, there is going to have to be some significant economic integration between the 17 members.

The Fiscal Compact Treaty, plans for a Banking Union, giving new powers to the European Central Bank, the European Court and to Brussels to oversee taxes and spending.

The Fiscal Compact Treaty's plan for a Banking Union could give new powers to the European Central Bank, the European Court and to Brussels. Credit: Julien Behal/PA Wire/Press Association Images

These are all things that many in London have accepted as inevitable if the Eurozone is to survive, and are prepared to go along with so long as the UK is not involved and they don’t impinge on our position within the single market.

But it is increasingly clear that plans for the next "great leap forward" go much further than doing what’s necessary to save the Euro.

Following hard on the heels of the Barroso speech came a wide-ranging list of proposals from a group of 11 EU states - led by the German Foreign Minister Guido Westerwelle - that would go way beyond anything that any UK Government (not just this one) could sign up to.

The list is spectacular in both its breadth and ambition.

There would be a directly elected European President and new powers for the European Parliament.

There would be a pan-European foreign ministry with greatly expanded powers to run an EU foreign policy decided by majority voting (so no vetoes by the UK or anyone else).

Defence policy would also be Europeanised, with the explicit aim that “this could eventually involve a European army”.

There would be a new EU police organisation to guard all external borders, with all visas run from Brussels.

If Cameron were to be confronted with demands for small treaty amendments, a power transferred here, a competence enlarged there, he would be harried constantly by his Eurosceptic backbenchers over whether it is sufficient to trigger a referendum, and whether such a vote should be about one particular issue or turned into a final decision on whether to get in or stay out.

If the ‘Westerwelle Group’ are serious, there will be no such ambiguity.

Cameron will say no, his coalition partners will be unlikely to complain and while Labour will exploit Britain’s isolation and diplomatic failure, they won’t argue with the substance.

As to where this would leave Britain’s membership of the EU? Well that would become a very real question, and one that - after three decades or more of ambivalence - we may no longer be able to avoid answering.